Gene Flow and Pollinator Behaviour in Silene dioica Populations

Westerbergh, Anna; Saura, Anssi

doi:10.2307/3546269

Cited by 63 publications

(49 citation statements)

References 28 publications

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“…In larger patches, distance flown between plants may be density dependent (Waddington, 1980;Heinrich, 1981;Schmitt, 1983a). Although pollinator flight distance between consecutively visited plants does not show exactly the pattern of gene flow, as carrying-over distance and gene flow by seeds could be greater and vary between pollinator species, a high number of visited flowers in the same plant will, generally, result in small distance of pollen carry-over (Levin, 1978;Handel, 1983;Schmitt, 1983a,b;Rasmussen & Brodsgaard, 1992;Westerbergh & Saura, 1994). Thus, gene flow by pollen for T. semitriloba, inferred by pollinators flight behavior, may be restricted and genetic neighborhood (Wright, 1940) may include just nearest neighbors.…”

Section: Discussionmentioning

confidence: 99%

Foraging behavior of bee pollinators on the tropical weed Triumfetta semitriloba: flight distance and directionality

2000

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We studied flight distance and directionality of bee pollinators on the tropical shrub weed Triumfetta semitriloba Jacq. (Tiliaceae), addressing (1) within-and between-plant movement pattern; (2) distances flown between plants; (3) flight directionality. Flowering plants were distributed in well-delimited clumps, in each of two pasture areas (A1 and A2) and one area of forest gap (A3), in Viçosa, southeastern Brazil. Five solitary bee species, Augochlorella michaelis, Augochloropsis cupreola, Pseudocentron paulistana, Ceratinula sp., Melissodes sexcincta, and two social bee, Plebeia droryana, P. cf. nigriceps were observed. All species moved mainly to the nearest flower on the same individual plant and, in between-plant movements, to the first or second nearest neighbor. All species moved non-randomly, presenting a flight directionality in departures (maintenance of flight direction), but with a high frequency of turn angles. It is suggested that this foraging behavior pattern occurred because of the resource quantity and quality (pollen or nectar), and environmental characteristics such as flower density and resource distribution.Key words: foraging behaviour, directionality, pollination, flight distance, solitary bees. RESUMO Comportamento de forrageamento das abelhas polinizadoras da planta invasoraTriumfetta semitriloba: distância de vôo e direcionalidade Estudamos a distância de vôo e a direcionalidade de abelhas polinizadoras da planta invasora Triumfetta semitriloba Jacq. (Tiliaceae), sobre os seguintes aspectos: (1) padrão de movimentação dentro e entre plantas; (2) distância de vôo entre plantas; (3) direcionalidade de vôo. As plantas floridas eram distribuídas em manchas bem delimitadas, em duas áreas de pasto (A1 e A2) e uma área de clareira de mata (A3), em Viçosa, MG, Sudeste do Brasil. Foram observadas cinco espécies de abelhas solitárias, Augochlorella michaelis, Augochloropsis cupreola, Pseudocentron paulistana, Ceratinula sp., Melissodes sexcincta e duas espécies sociais, Plebeia droryana, P. cf. nigriceps. Todas as espécies moveram principalmente para a flor mais próxima, dentro da mesma planta e, nos movimentos entre plantas, para o primeiro ou segundo vizinho mais próximo. Todas as espécies apresentaram uma direcionalidade no padrão de vôo, ou seja, uma movimentação não aleatória, mas com uma alta freqüência de ângulos laterais. Sugere-se que esse padrão de comportamento de forrageamento ocorreu devido à qualidade e quantidade de recurso (pólen ou néctar) e às características ambientais como a densidade de flores e distribuição do recurso nas manchas.Palavras-chave: comportamento de forrageamento, direcionalidade, polinização, distância de vôo, abelhas solitárias.

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Section: Discussionmentioning

confidence: 99%

Foraging behavior of bee pollinators on the tropical weed Triumfetta semitriloba: flight distance and directionality

2000

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“…Furthermore, isolated plant populations may suffer from genetic erosion that diminishes reproductive success (Oostermeijer et al 1994;Westerbergh and Saura 1994;Matthies et al 1995).…”

Section: Changes In Reproductive Successmentioning

confidence: 99%

“…Field studies are complicated by the fact that increasing fragmentation or isolation of habitats changes not only pollinator diversity but also other factors possibly influencing seed set like patch size and density of flowering plants, occurrence of competing alternative flowers (Klinkhamer and de Jong 1990;Jennersten and Nilsson 1993;Kunin 1993;Conner und Rush 1996), genetic variability, (Olesen and Jain 1994;Oostermeijer et al 1994;Van Treuren et al 1994;Westerbergh and Saura 1994;Matthies et al 1995) and abundance of herbivores (Kruess and Tscharntke 1994;Strauss et al 1996). Furthermore, seed set may be resource limited, but not pollinator limited, and therefore reductions in pollinator abundance would be less important (Bierzychudek 1981;Horvitz and Schemske 1988;Burd 1994).…”

Section: Introductionmentioning

confidence: 99%

Effects of habitat isolation on pollinator communities and seed set

1999

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Destruction and fragmentation of natural habitats is the major reason for the decreasing biodiversity in the agricultural landscape. Loss of populations may negatively affect biotic interactions and ecosystem stability. Here we tested the hypothesis that habitat fragmentation affects bee populations and thereby disrupts plant-pollinator interactions. We experimentally established small "habitat islands" of two self-incompatible, annual crucifers on eight calcareous grasslands and in the intensively managed agricultural landscape at increasing distances (up to 1000 m) from these species-rich grasslands to measure effects of isolation on both pollinator guilds and seed set, independently from patch size and density, resource availability and genetic erosion of plant populations. Each habitat island consisted of four pots each with one plant of mustard (Sinapis arvensis) and radish (Raphanus sativus). Increasing isolation of the small habitat islands resulted in both decreased abundance and species richness of flower-visiting bees (Hymenoptera: Apoidea). Mean body size of flower-visiting wild bees was larger on isolated than on nonisolated habitat islands emphasizing the positive correlation of body size and foraging distance. Abundance of flower-visiting honeybees depended on the distance from the nearest apiary. Abundance of other flower visitors such as hover flies did not change with increasing isolation. Number of seeds per fruit and per plant decreased significantly with increasing distance from the nearest grassland for both mustard and radish. Mean seed set per plant was halved at a distance of approximately 1000 m for mustard and at 250 m for radish. In accordance with expectations, seed set per plant was positively correlated with the number of flower-visiting bees. We found no evidence for resource limitation in the case of mustard and only marginal effects for radish. We conclude that habitat connectivity is essential to maintain not only abundant and diverse bee communities, but also plant-pollinator interactions in economically important crops and endangered wild plants.

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“…Our data show that Gomortega keule is predominantly visited by syrphid flies in late March -early April, and that syrphids carry a greater proportion of G. keule pollen than other insects that were collected on the trees. Although some authors suggest that syrphids may be inefficient pollinators, numerous studies have shown that syrphids are important pollinators for a range of species (Schmid 1970, Garcia & Chacoff 2007, Elam et al 2007, Cronk 2000, Percy & Cronk 1997, they are found in most terrestrial habitats (Dziock 2006), and they may be effective through shear frequency of visitation or because of their foraging behaviour and abundance (Westerbergh & Saura 1994).…”

Section: Discussionmentioning

confidence: 99%

Flower and fruit production and insect pollination of the endangered Chilean tree, Gomortega keule in native forest, exotic pine plantation and agricultural environments

Lander¹,

Boshier²

2009

Rev. chil. hist. nat.

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This study was undertaken to discover whether patterns of flower and fruit production for Gomortega keule, an endangered Chilean tree, differ between exotic pine plantation, agricultural and native forest environments. A pilot study was also undertaken to identify the primary pollinators of G. keule. Although similar proportions of G. keule trees flowered in the agricultural and native forest areas, more trees in the agricultural sites produced fruit compared to trees in the native forest sites. Flowering and fruiting of G. keule was extremely rare in the exotic pine plantations. Our data show that G. keule flowers are predominantly visited by syrphid flies in March-April, and that syrphids carry a greater proportion of G. keule pollen than the other insects collected. Native forest and low intensity agricultural systems appear to provide habitat in which syrphids forage and G. keule is able to produce fruit successfully, but exotic pine plantation does not; suggesting that a landscape made up of a mosaic of different landuse types is not necessarily inimical to the continued reproduction of G. keule, but that the combination and types of landuses and intensity of management must be carefully considered.

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Gene Flow and Pollinator Behaviour in Silene dioica Populations

Cited by 63 publications

References 28 publications

Foraging behavior of bee pollinators on the tropical weed Triumfetta semitriloba: flight distance and directionality

Foraging behavior of bee pollinators on the tropical weed Triumfetta semitriloba: flight distance and directionality

Effects of habitat isolation on pollinator communities and seed set

Flower and fruit production and insect pollination of the endangered Chilean tree, Gomortega keule in native forest, exotic pine plantation and agricultural environments

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